단열 측면 벽을 갖는 수직 환형 내의 유체충의 축대칭 열 불안정성

유주식,박승수 安東大學校 工業技術硏究所 2000 공업기술연구논문집 Vol.7 No.1

본 연구에서는 측면벽이 단열된 수직 환형 내에 있는 유체충의 축대칭 열불안정성을 조사한다. Galerkin 방법을 이용하여 임계 Rayleigh 수를 계산한다. 가장 불안정한 모드는 수직 방향으로 하나의 구조를 갖고 있으며 불안정이 일어나는 순간은 주로 환형의 폭에 의해 결정된다. 환형의 폭이 증가할수록 임계 Rayleigh 수는 감소한다. 단열 측면벽을 갖는 환형의 임계 Rayleigh 수는 전도 측면벽을 갖는 환형의 것보다 작다. This study investigates axi-symmetric thermal instability of a fluid layer confined in a vertical annulus with insulating lateral walls. The critical Rayleigh number is calculated by using the Galerkin method. The most unstable mode has one-roll structure, in the vertical direction, and the onset of instability is mainly dependent on the gap width of the annulus. As the scaled gap width increases, the critical Rayleigh number decreases. The critical Rayleigh number for an annulus with insulating lateral walls is smaller than that of the annulus with conducting lateral walls.

링 예약 알고리즘을 이용한 ATM 스위치

주우석,박경희,유승열,최병석 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

We propose a new architecture of multicast ATM switch which has input and output buffers and uses Multicast Ring Reservation Algorithm to resolve output port contention. This new algorithm eliminates internal cell loss due to contention, and reduces the hardware complexity. We can dynamically control the number of cells routed to a specific output port during one cell time with this contention resolution algorithm. The computer simulation is performed under bursty traffic condition to show the performance of this proposed multicast ATM switch.

과재하중 재하에 따른 역 T형 옹벽의 활동거동에 관한 수치해석

유남재,이명욱,박병수,이승주 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

This paper is experimental and numerical research about the sliding behavior of cantilever retaining walls resisting surcharge loads. In experimental research, centrifuge model tests at the 1g and 40g-level were performed by changing the location of model footing and its width. Bearing capacity of model footing and characteristics of load-settlement and load-lateral displacement of retaining wall were investigated. Test results of bearing capacity were compared with modified jarquio method, based on the limit equilibrium method with elasticity theory. For the numerical analysis, the commericially available program of FLAC was used by implementing the hyperbolic constitutive relationships to compare with test result about load-settlement and load-displacement of retaining wall, bearing capacity of strip footing.

외측 도달법에 의한 원위 상완골 간부 골절의 수술적 치료

이승구,이주엽,서유준,이준호,안농겸 대한골절학회 2004 대한골절학회지 Vol.17 No.2

이면성 및 도플러 심초음파도를 이용하여 진단한 선천성 거대 좌회선지-좌심실 관동맥루

진승원,박준철,이영중,유병현,박현옥,김용주,윤호중,김재형,홍순조,최규보,권종범,원용순,박건 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.4

골프지도자의 자격유형에 따른 교육적 기반과 생활환경에 관한 연구

백병주,유승원 龍仁大學校 體育科學硏究所 2003 體育科學硏究論叢 Vol.13 No.1

This study aims to provide cultural and technical information and data on golf instructors' educational and personal life and their social status by closely examining their lifestyle revolving mostly around the golf range. After entering into the world of golf, many, if not all, of them commit themselves fully to golf in terms of money and effort over a long period of time in order to improve skills as a golfer. And after playing in a number of amateur golf tournaments and passing a sort of exams designed to test their qualification, they eventually get into the world of professional golf. Their life pattern changes gradually to suit a particular league or tournament. Through the change that often entails anguish and conflicts, golf players become more mature and develop ability to teach others. Starting fresh as an instructor, they attempt to teach students based on strategies and skills, which are systemized to some extent but focused mainly on practical training at the same time. In this period of their life, golf instructors usually try to rectify personal shortcomings and improve financial conditions while bracing for a second life as a player. These efforts, however, bring both positive and negative emotions to them. Consequently, they become confused as to what their own identity really is. And they instinctively try to get over this hardship through self rationalization. But the anguish and conflicts bothering them are not easily removed. The study result mentioned above gives us problems as well as implications to consider from the viewpoint of pedagogy, and they are as follows: First, as the function of a golf range and golf-related policies is tilted overly toward profit-making not just in terms of the substitution effect relating to physical education and workout practiced in daily life but also in terms of "money earning more money," golf is largely commercial and private. That commercial motivation prevails over educational functionality when it comes to a golf range or related policies is a serious matter. Therefore, a large sum of investment is absolutely necessary to nurture an excellent player. And this is why golf is regarded by many ordinary people as something very different from other sports. In view of this peculiar aspect, agencies and organizations responsible for raising and training golf players and instructors must offer programs that are designed to provide effective and practical training to those aspiring to become a player or an instructor. In so doing, they need to pay attention to cost saving and other productive measures so as to ultimately transform golf education into a complementary/substitute means to traditional physical education and daily physical exercise. Second, in most cases, golf ranges and instructors seem to devote too much of their time and resources to teaching practical skills and tips rather than to developing intellectual capability and educational acumen of students and trainees. This problematic aspect or trend, which stems largely from Korea's elitist physical-education policy, can be wiped out only when we do away with excessive commercialism and materialism noted by endless pursuit of mundane fame and wealth and instead assign a higher level of value to the education designed to teach true knowledge and morality. Also, a systematic educational foundation should be prepared so that golf can be accepted and played more widely in the future. Third, the job insecurity and low social status of golf instructors make their attempt at second life as a player all the more difficult. The two problems also push golf instructors to focus increasingly on money-making. The unstable identity of golf instructors is directly related to the current educational environment in which a golf instructor is perceived to be teaching practical skills for a particular sport instead of teaching physical-education in a broad sense. Solving the less-than-desirable situation requires institutional support in the form of proper environment for various physical activities and feedback, seminars on continuing education, public space for self development, education-related public offices offering space, assistance and incentives, and job security. Fourth, we are living in the era of "education inflation" here in Korea. Educational background must not mean everything in and for one's life. But it may be necessary for an instructor to gain confidence and respect from the public. In this regard, if it is deems that the overall level of education for golf instructors is low, it is important to add more programs and classes to the existing curriculum so as to help instructors develop intellectual strength to work comfortably with complicated topics. It is true that the word 'golf instructor' still sounds strange to ordinary people and even some of those involved in physical education. But this much is true. Golf instructors are shouldering their share of the burden for physical education, and their endeavor is making golf become more and more popular. confused due to irrational circumstances and policies, golf instructors in Korea, however, will surely play a pioneering role for the nation's future education. In consideration of this, the government must actively lend a helping hand to them.

자동 경계 탐지(Automated Border Detection)심초음파도를 이용한 좌심방 면적 및 기능의 평가

김현주,주승재,임진형,정효균,이영수,유호대,차태준,이재우 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.2

인공 해수분위기에서 저탄소강의 부식특성에 미치는 합금원소 Cr, Co 및 W의 효과

심재주,유승재,최윤석,김정구,유장용 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12

The aqueous corrosion characteristics of 1% Cr-steel alloyed with small amounts of Co and W, in synthetic seawater was studied by using immersion weight-loss tests, electrochemical corrosion tests (potentiodynamic test and electrochemical impedance spectroscopy (EIS) measurements) and analytical techniques. 1% Cr steels containing Co or W from 0.2 to 0.4 wt.% showed higher corrosion resistance than the 1% Cr steel in the immersion and potentiodynamic tests. EIS measurements showed that the Nyquist plot presented one time constant. Furthermore, the Co- and W-bearing steels present higher Rp values than the 1% Cr steel through all the test period. The better corrosion resistance of the Co-and W-bearing steels is attributed to protectiveness of the surface layer. The corrosion products were examined using electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The results of EPMA indicated that Cr was concentrated in the inner region of the rust layer, while Co and W were distributed all over the rust layer. XPS results showed that Co existed as a trivalent oxide in the rust layer and W in the rust appeared in the form of a WO₄ compound.

순차적 크리깅기법을 이용한 미소혼합기의 최적화

박재용,유진식,황승민,임민규,오영규,김용대,한석영,맹주성 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

An active micro-mixer, which is composed of an oscillating micro-stirrer in the micro-channel to provide effective mixing was optimized. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight micro-channel and micro-channel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interaction after the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced' and stabilized. Therefore, an approximate optimization of an active micro-mixer with an oscillating stirrer was performed using Kriging method with OLHD (Optimal Latin Hypercube Design) in order to determine the optimal design variables. The design parameters were established as the frequency, the length and the angle of the stirrer. The optimal values were obtained as 1.5754, 0.803D and ±45°, respectively. It was found that the mixing index of the optimal design increased by 83.36% compared with that of the original design.

소아에서의 급성 파종성 뇌척수염의 임상적 고찰

조수진,박은애,유은선,김혜순,손세정,서정완,이승주,한후재 이화여자대학교 의과대학 2003 EMJ (Ewha medical journal) Vol.26 No.2

목적: 급성 파종성 뇌척수염은 감염이나 예방 접종 후 발생하는 중추 신경계의 급성 자가 면역 염증성 질환으로 탈수초를 일으킨다. 신경학적인 증상으로 발현되고 대부분 환전히 회복되지만 신경학적 후유증을 남기거나 사망 할 수도 있다. 이에 저자들은 본원에서 발생 한 14명을 분석하여 조기 진단과 치료에 도움을 주고자 하였다. 대상과 방법: 1998년 3월부터 2003년 8월까지 이대목동병원에서 급성 파종성 뇌척수염으로 진단 받은 14명의 의무기록을 후향적으로 조사하였다. 결과: 환자들의 평균 발생 연령은 5±7.8개월이였고, 특정계절이나 연도에 집중되어서 나타나지는 않았다. 선행질환은 주로 비특이적인 상기도 감염이 가장 많았고, 초기증상으로는 경련이 가장 많았다. 그 외에 의식저하나 운동장애도 있었다. 뇌척수액 검사에서 백혈구 증가증이 발견된 경우는 있었으나 단백이 증가된 경우는 없었다. 뇌 자기공명 촬영에서 T2 증강시 뇌백질과 기저핵에 고음영의 다발성 병소가 발견되었고 추적 촬영에서 대부분에서 소실되었다. 뇌파 검사가 시행되었던 경우 전반적인 서파가 가장 많았고 국소적인 극파가 나온 경우도 한 명 있었다. 환자들은 정맥 면역 글로블린과 메틸프레드니졸론으로 치료하였고 치료 시작 후 3~7일내 증상이 호전되었다. 모든 환자를 2달 이상 추적 관찰하였고 항경련제가 지속적으로 필요한 정도의 경련성 질환이 두 명, 신경아교증이 남아잇는 경우가 한 명, 외래에서 다발성 경화증이 의심되는 경우가 한 명 있었다. 결론: 급성 파종성 뇌척수염은 침범 부위에 따라서 다양한 임상 상으로 나타나며 면역 글로블린과 메틸프레드니졸론이 치료에 효과적이였다. 본 연구에서는 대상 환자수가 적어 신경학적 후유증의 위험요소는 밝힐 수는 없으나, 예후는 검사소견과 연관되어 있지는 않았고, 대부분에서 양호하여 완전히 회복되었으나, 신경학적 후유증이 남은 경우도 있었다. Objective:Acute disseminated encephalomyelitis(ADEM) is an acute demyelinating autoimmune inflammatory disease of the central nervous system which develops after infection of vaccination. It may be fatal, and produce a permanent residual static disability or fully recover. We retrospec-tively studied 14 cases to investigate the clinical findings and outcome of ADEM. Methods : 14cases of ADEM diagnosed at Ewha Womans University Mokdong Hospital from 1998 to 2003 were retrospectively reviewed. Results : The age of onset was 5years±7.8 months and no seasonal clustering was found. The time of onset of symptoms was between 3 to 30 days. The preceding events were nonspecific upper respiratory infections in 9 cases, aseptic meningitis in 4 cases, and gastroenteritis in one case..The initial symptoms were seizure, altered consciousness, hemiparesis, fever, headache, and vomiting. Brain MRI showed multifocal high signal intensity lesions on T2 weighted image mainly in the cerebral whith matter, basal ganglia and periventricular white matter. EEG was performed in some cases and showed generalized or focal slow waves and only one case showed focal spikes. Patients were treated with IV globulin and methylprednisolone and the symptoms improved within 3-7 days after treatment. All patients were followed up for more than 2 months and most of them fully recovered except two. Conclusion : ADEM presents in various clinical manifestations depending on its involvement of the brain lesions. Most cases recovered fully but in some cases, residual permanent neurologic sequelae remained.